Hi All,
Still looking for different components for my project. What would you say about Bell intercoolers - are they high enough quality? www.bellintercoolers.com
I don't want to go cheap Ebay route but I don't feel like paying for Blitz etc. - I don't believe that cost is fair.

Thank You
Ted

 

Good quality intercoolers. Corky Bell who owns it is pretty well known and respected in the turbocharged industry. I have used a few of their intercoolers on previous RX7's I have owned and been happy with the way they performed.

 

Here is some good reading:

http://www.bellengineering.net/Pages...cts_books.html

 

Thanks mate!

Cheers
Ted

 

Does anyone think there's much to be gained by swapping out the intercooler that shipped with the GReddy?

 

No.
You won't gain a bit. IF you run Greddy turbo, at the pressure it is running, i't own cooler will work just fine.

Also ebay Intercooler are not that bad either. I have 2 of different sizes. one is real 13" wide x 3" thick, I used at the beginning, but then decided to switch to a smaller one. i forget what the dimensions are but it is about the same as greddy. and the smaller one cools the charge just as good.

 

OK than, I will ask something that is surely discussed many times before. Brand vs. Ebay intarcooler.
Problem is that many people say "don't go cheap" and others say that ebay advertised items are fine. But no one is giving actual difference from tech. point of vew.
1. Is there difference in fabrication quality - welds etc.?
2. Is there difference in design (In fact I would think that they are very much identical in design) and performance? Heat exchange efficiency, pressure drop?
3. Difference in alu grade used? Althought we don't need nothing fancy here.

I understand that not all ebay IC's are the same but does anyone know of "ebay brand" that is just as good as more established makers? By the end it is not a rocket science isn't it? I would guess that if someone is buying good quality core and has moderate expertise in alu welding and fabricating than he should do just fine. Am I all wrong here?

Cheers
Ted

 

Here is some more information on different types of intercoolers.

http://www.are.com.au/techtalk/intec...e%20and%20Fin?

 

Thanks Colin! I will read it now!

Cheers
Ted

 

You should qualify that a bit.
If you run the boost level at which the kit ships, it is more than enough.
If you are running the turbo at the end of its flow map (in the 12 PSI range, you might benefit from a better intercooler.
Yo would need measurements of the intercooler outlet temps to know for sure.

E-Bay intercoolers are acceptable as long as the end-tanks are well designed.
That is where he real engineering goes on more expensive intercooler.
The cores are all about the same.

 

To qualify:
I don't mean 12# on Greddy Turbo. If one wants to run 12# of boost in RX8 I'd say Greddy is a REALLY poor choice, and the intercooler is far from the first thing that needs to be upgraded in this case.
What I mean 6-9 PSI is what majority of folks are running. At that rate swapping to a different cooler will not make any noticeable difference.

"The cores are the same"^^ . Exactly!
If I am not mistaken, someone on my tread wrote that he was one of the people who started this intercooler thing on ebay. He bought a large intercooler from some reputable manufacturer, and then made 2 out of it and was selling them on ebay, or something like that.

I own 2 of ebay ones brand, and as far as the quality of fabrication, they are very well made. Weld quality, finish and all that.
The job they do cooling charge is just as good too.

Off course I do not have any exact numbers to give here, as I never measured the flow, pressure drop, the efficiency or any other criteria, but then again, the palm of my hand tells me that after driving for 20 miles one side of it is hot and the other is cold to the touch. The boost came at 3500 RPM without the cooler, with the larger one, and the smaller one alike. The difference is practically unnoticable. And on top of it all they cost me like 60-70 bucks a piece...

This may not be the case with Greddy though, putting a large intercooler on with Greddy may actually introduce additional time it would take to pressurise it (due to the size of the turbine), thus postponing the point where the full boost comes.

We all know that Greddy turbo is not capable of keeping up with the Rennys redline and the pressure drops at 6-7 K. With larger cooler it may start dropping even earlier, as there is more to fill, more volume to move and more resistance to push against... and so in the end the grater deal of strain will be put on the turbine, thus reducing it's efficiency...

"The closer to ambient temperature the intake charge gets cooled to, the exponentially larger the internal surface area of the core is needed, also exponentially increasing the friction (drag) of the charge air in the larger core, causing higher Static pressure drop. Please note that the same kw. output can be generated by two engines, but require two different intercoolers. If one engine is fitted with a smaller than optimum turbo, then it will operate out of it's efficiency range, over revving & 'beating' the air, to a higher temperature."
See: http://www.are.com.au/techtalk/intec...0!%20!%20!%20!


Again I am neither trying to advocate ebay stuff, nor knock Greddy. I am just answering to a question posted earlier.

"Does anyone think there's much to be gained by swapping out the intercooler that shipped with the GReddy?"

From my personal experience NO. At least nothing that is worth spending the extra money on.

Now if you run a larger turbo, t3-t4 or a bigger one at 12-14 PSI, you may need all the cooling efficiency you can get, and a better quality brand might be the answer.

 

I've only got a second right now, so I can't go into the other stuff in you reply right now.

However, this statement is indicative of other problems in your argument.

The GReddy turbo's boost curve has nothing to do with its efficiency.
This is a turbine issue (WG).

The flow characteristics of an intercooler don't have much to do with its size and the pressurization time between a GReddy kit sized intercooler and one the size of the entire car would only be fractions of a second.

Remember, you are pushing upwards of 500 CFM through it.

 

MM I have a feeling that we are talking about the same thing, but Just using different words. You are correct turbo efficiency has nothing to do with its boost curve.
I used the word efficiency here in relation to the system as a whole, not the turbine. I guess Efficiency is not the right word to use here in the first place, Effectiveness would describe it better in this case.

 

Either way, the scenario you propose is incorrect.

1) Within practical limits, intercooler size does not affect lag
2) The loss of boost in higher RPMs is not the result of the turbo - its backpressure against the wastegate
3) The efficiency of the intercooler directly affects the potential for boost

 

Ok, and where did I say it does?
I actually said that I run my system with both intercoolers and without one, and did not see any noticeable changes in terms of how soon boost came.
What I did say was that the large intercooler may reduce the effectiveness of an undersized turbo (Effectiveness in relation to performance of the vehicle, not ability to flow air).
I never said anything about how much, but you can't argue the fact that a greater space takes longer to pressurise. ( a fraction of a second in this case, but longer nevertheless).
Man you are good with formulas, try and calculate how much air can be compressed into the 1 cf in order to get it to say 9PSI af 500 CFM flow rate with the engine sucking out whatever amount of air it needs at given rpm and pressure? We are pretty much trying to pressurise an open ended tube.

Just for the sake of argument can someone figure out how much air our engine pumps at 9K rpm given that the intake pressure is 9psi?

I bet the time to pressurise that 1 cfm of space suddenly start increasing, or may not even be achievable in the first place at that rate. In order to pressurise you need to feed more air in than there comes out. Can Greddy flow this much?

You mean that waistgates lick air? All of them?
Are you implying that if you weld the waistgate on Greddy turbo, shut. the turbine will be able to maintain and build pressure effectively all the way to the redline?

Isn't it what I said before? Off course it does. However just like you are saying "Within practical limits, intercooler size does not affect lag", I am saying that within the given application (Greddy @ 6-9 PSI) a more efficient intercooler may not make any usable difference. And a bigger intercooler in this case does not mean more efficient.
No matter how efficient the intercooler is, if it is air to air, it won't cool below the ambient temperature. In fact it won't even cool down to the ambient temperature.

MM I am not trying to argue or prove you wrong, I am just trying to understand your take on it and explain myself.

 

I would point it out, but you went back and edited that reference out of your previous post 10 minutes after this last response.

As a matter of fact, I was about to give responses to a bunch of stuff in you series of posts.
However, now seeing that you substantially changed the content of your posts in a manner as to make my points seem argumentative rather than informative, I'm not going to dignify your responses at all.
Go figure out the math yourself.
I'm sure you can post the results equally retroactively.

 

MM, the only one post I edited in this conversation was edited by me right at the time I wrote it. Last night:
Last edited by rotorocks : Today at 02:31 AM.
In fact I changed it to ad an quote from the article posted earlier in the tread and to further explain myself.

I have not edited any other posts.
As I said I am not trying to argue. Not by any means.
You yourself told me that I an incorrect, and earlier you asked that I qualify . I am just trying to paint the picture the way I understand it, and I tell you why I think I am not wrong. How is it argumentative?
In any case, If you take it personally, that is a different story. But no need to accuse me of changing the content of my posts as to make you look bad. I simply do not do things like that.
If I am mistaken, I admit my mistakes if I believe that I am not I want to understand where I am wrong.
As for the math, I am just not that good at it, to do this sort of calculations. I think in ictures, not numers and understand things conceptually.

 

Well, your original post said bigger ICs will induce slower boost response. They won't. It doesn't work quite like that.

I'll refer you to https://www.rx8club.com/series-i-tech-garage-22/rotary-math-106294/
PSI isn't the whole story - you NEED to know IC outlet temps.
But for the sake of argument, we'll use 120°F.

ROTARY VOLUMETRIC FLOW RATE

VFR = ((DISPLACEMENT) x (RPM) ÷ 1728) x (VOLUMETRIC EFFICIENCY)
VFR = ((80cid) x (9200rpm) ÷ 1728) x (87%)
VFR = (425cfm) x (.87)
VFR = 369.75 cfm

ROTARY MASS FLOW RATE

MFR = (2.703) x (Pa) x (VFR) ÷ (Ta + 460)
MFR = (2.703) x (14.7) x (369.75) ÷ (120° + 460)
MFR = (14691.683) ÷ (545)
MFR = 25.32 POUNDS per MINUTE (lb/m)

So, at a Pr of 1.52 (which is 9 PSI of boost)

Pr x MFR = MFRboost
1.52 x 25.32 = 38.49 lb/min

Its about 503 CFM.


I'm not quite sure what you are asking, but yes - the GReddy turbo can flow that much, but it is reaching the end of its efficiency range, so you start to up the temp numbers for the above formula which starts to reduce the mass flow rate - not the volume flow rate.


Absolutely. You will pop the housings right open with tons of pressure - at a really high temperature.
The MFR will flatten out, but the VFR will continue to increase.
The pressure in the turbine section is what is killing the turbo, not the compressor efficiency.
An external wastegate will stop this, but you will still be generating 30 PSI of back pressure in the exhaust.

The reason I provided the two spreadsheets and formula sets in the aforementioned thread was to avoid blind speculation and flat out inaccuracies like what you are putting forth.
You built your own system - so check out for sure what you have accomplished - do the math.

 

Now this is dome great info...
With this now I even begin to understand what I may need to do to improve my system.
I really appreciate it. Thanks.
And thanks for reconsidering not answering my posts.

 

So, uh, with a GT35r or 3071 turbo, would an intercooler upgrade from the one that shipped with the GReddy kit (& that fits without tearing the whole bloody car apart) yield a significantly more dense charge into the engine at, say, 10 psi?

Enough to make more power on crappy CA 91 octane without pulling more than 2 degrees of timing per # of boost...or maybe even not having to pull as much timing?

 

https://www.rx8club.com/showthread.php?t=106294

 

Sorry for the head-banging, mate. Thanks for the hook-up on the engineering ****!